The prior art has for some time described machines performing a compacting operation on damp solid refuse, for example from animal discharge gutters, but also from industrial processes, sewage discharge, livestock establishments, and in general from all processes producing solid waste containing a considerable quantity of water. The machines include the use of an Archimedes screw which transports the waste from a loading zone, in which the waste is introduced into the machine, for example by a hopper, towards a discharge zone in which the waste, after being freed of the humid part and compacted, is discharged. In the loading zone, or immediately downstream thereof, a perforated drainage grid is usually provided which enables an initial drainage of liquids in order to free the waste from the greater part of the liquids. The grid is generally placed at the start of the Archimedes screw as it is in this area that the liquid presence in the waste solids is at its greatest; the liquids in outlet from the grid are collected in an underlying zone of liquid collection, while the solid parts, freed from the liquids, are compacted and transported from the Archimedes screw to a discharge station situated downstream of the Archimedes screw.
The drainage grid includes an arched perforated portion which, during machine operation, must stay substantially in contact with the helix in order to optimise machine operation and enable transport of the solid substances as well as the drainage of the liquid.
The prior-art machines of this type exhibit some drawbacks. It has been noted that a solid body can become wedged between the drainage grid and the screw, which can cause, should the solid body be very hard (for example a stone), total arrest of the screw and can sometimes even damage it.
The aim of the present invention is to obviate the drawbacks encountered in the prior art by providing a machine in which the drainage grid adheres continuously to the screw helix.
An advantage of the present invention is that it maintains the grid in contact with the screw helix without there being any need for an operator to intervene.
A further advantage of the present invention is to enable the machine to continue functioning, without any danger of damage, even in cases where a solid body gets in between the grid and the screw helix.
These aims and more besides will be explained in more detail during the course of the following description, are substantially attained by the machine as it is described and claimed in the present patent application.